function writeCookie(name,value,days) {
	// By default,there is no expiration so the cookie is temporary
	var expires = "";
	// Specifying a number of days makes the cookie persistent
	if(days) {
		var date = new Date();
		date.setTime(date.getTime() + (days * 24 * 60 * 1000));
		expires = "; expires = " + date.toGMTString();
	}
	// Set the cookie to the name, value, and expiration date
	document.cookie = name + "=" + value + expires + "; path=/";
}

function readCookie(name) {
	// Find the specified cookie and return its value
	var searchName = name + "=";
	var cookies = document.cookie.split(";");
	for(var i=0;i<cookies.length;i++) {
		var c = cookies[i];
		while (c.charAt(0) == '')
			c = c.substring(1,c.length);
		if(c.indexOf(searchName) == 0) 
			return c.substring(searchName.length, c.length);
	} 
	return null;
}

function eraseCookie(name) {
	// Erase the specified cookie
	writeCookie(name,"",-1);
}